Changes in the Activity of the Maturation-Promoting Factor Are Correlated with Those of a Major Cyclic AMP and Calcium-Independent Protein Kinase During the First Mitotic Cell Cycles in the Early Starfish Embryo

Many studies suggest that MPF activation depends on protein phosphorylation or that MPF is itself a protein kinase. In the present report, cyclic variations of MPF activity have been correlated in vivo with changes in the extent of protein phosphorylation or in vitro with changes of a major protein kinase during the first cell cycles of fertilized starfish eggs. This cycling protein kinase neither requires cAMP nor Ca²⁺. Neither colchicine nor aphidicoline, which inhibits cleavage and chromosome replication respectively, was found to suppress the synchronous and cyclic variations of both MPF and protein kinase activities. Protein synthesis was found to be required for both MPF and protein kinase activities to reappear after their simultaneous drop at the time of mitotic or meiotic cleavages. Production of either MPF or protein kinase activities is not the immediate result of protein synthesis since there is a delay at each cell cycle between the time when protein synthesis is required and the time when both MPF and protein kinase activities are produced. This suggests that both MPF and protein kinase activities might involve some post-translational modification of a precursor protein synthesized during the preceeding cell cycle.     

Human gut neuroanatomy: methodology for a quantitative analysis of nerve elements and neurotransmitter diversity in the human "enteric nervous system"

After a few decad of neglect, the "enteric nervous system" has recently regained the attention of investigators. Indeed, various studies, such as those which led to the isolation from the gut of a number of neuropeptides, subsequently demonstrated throughout the nervous system, have prompted major advancements of modern neuroscience. In spite of a wealth of animal investigations and a number of human studies, however, available information concerning the human "enteric nervous system" is comparatively sparse. In the opinion that such lack of information was largely due to unavailability of appropriate techniques, we have initiated and developed a new comprehensive methodology. This way, a quantitative analysis was made possible of both nerve structure and transmitter status, point-to-point along the gut, as well as within the various, functionally heterogeneous components of the gastrointestinal wall itself. After a general introduction, the present review is intended to summarize such methodology, with the addition of a few illustrative examples of application and a practically-oriented guideline to its use, in the form of technical appendix.     

Reactivity of the fructose 1,6-bisphosphate-activated pyruvate kinase from Escherichia coli with pyridoxal 5'-phosphate

The allosteric fructose 1,6-bisphosphate-activated pyruvate kinase from Escherichia coli was modified with pyridoxal 5'-phosphate in the presence and in the absence of phosphoenolpyruvate, fructose 1,6-bisphosphate, MgADP and MgATP. In all cases a time-dependent inactivation was observed, but the rate and the extent of inactivation varied according to the conditions used. The kinetic properties of the partially inactivated enzyme were differently modified by addition of substrates and effectors to the modification mixture, the parameters mostly affected being those concerning fructose 1,6-bisphosphate. Tryptic peptides obtained from fully inactivated pyruvate kinase in the different conditions have been separated. In all conditions three main 6-pyridoxyllysine-containing peptides were present, the amounts of which showed significant differences in the presence of fructose 1,6-bisphosphate and MgADP. The function of the labelled peptides and the evidence supporting the physical existence of different conformational states are discussed. The main conclusion concerns the involvement of one of the above peptides in the binding of the allosteric effector fructose 1,6-bisphosphate.     

中国平脉树螽属五新种记述：直翅目：螽斯科：树螽亚科

本文报道中国平脉树螽属5个新种。每个新种皆有详细的形态描述和形态特征图。所有模式标本存于北京农业大学昆虫标本室。     

Changes in Abscisic Acid Content in Axis and Cotyledons of Developing Phaseolus vulgaris Embryos and their Physiological Consequences

Prevost, I. and Le Page–Degivry, M. Th. 1985. Changesin absicisic acid content in axis and cotyledons of developingPhaseolus vulgaris embryos and their physiological consequences.—J.exp. Bot. 36: 1900–1905.Changes in abscisic acid (ABA)content with time were measured in embryonic axes and in cotyledonsof Phaseolus vulgaris embryos using a radio–immunoassay.During embryogenesis, a similar pattern was observed in bothtissues: ABA increased to a maximum 29 d after an thesis, followedby a decrease as the seed matured. The level of ABA in the cotyledonswas always much higher than that in the axes. In in vitro cultures,the duration of the lag phase before germination of isolatedembryonic axes increased with ABA content. The presence of cotyledonsalways lengthened the lag phase; longer lag phases were associatedwith greater concentrations of ABA in the cotyledons. Moreoverthe presence of cotyledons stimulated the growth of seedlings. Key words: ABA distribution, embryo maturation, axis and embryo germinability     

Relationships Between Cytoplasmic Filaments and Nuclear Envelope in Teleost (Pimelodus maculatus) Endothelial Cells

In the present report a characteristic pattern showed by cytoplasmic filaments (intermediate-sized and actin-like) in the perinuclear area of a freshwater teleost (Pimelodus maculatus) endothelial cells is described for the first time. Thus, many intermediate-sized filaments are directly inserted in the nuclear envelope, but others are connected to one another and to the nucleus through microfilaments. It is suggested that these particular relationships between the nucleus and cytoplasmic filaments are responsible not only for nuclear anchorage, but also for nuclear movements     

Monitoring the persistence of Laccaria bicolor as an ectomycorrhizal symbiont of nursery-grown Douglas fir by PCR of the rDNA intergenic spacer

The large-scale inoculation of selected beneficial ectomycorrhizal fungi in forest nurseries has generated renewed interest in the ecology of these symbiotic fungi. However, information on the dissemination and persistence of introduced symbionts is scarce due to the limitation of the current identification methods. To identify ectomycorrhizal fungi on single root tips, we investigated the polymorphism of the PCR-amplified ribosomal DNA intergenic spacer (IGS) from a wide range of ectomycorrhizal fungi. To investigate the reliability of this molecular approach in large-scale surveys, the dissemination and persistence on Douglas fir seedlings of the introduced Laccaria bicolor S238N were assessed in a forest nursery in the Massif Central (France). Several hundred ectomycorrhizas and fruiting bodies were sampled from plots where control and L. bicolor inoculated-Douglas fir seedlings were grown for 1.5 years. PCR typing of mycorrhizas indicated that trees inoculated with L. bicolor S238N remained exclusively colonized by that isolate (or sexually derived isolates) for the entire test period. In contrast, control seedlings were infected by indigenous isolates of Laccaria laccata and Thelephora terrestris. The molecular evidence for the persistence of the introduced mycobiont despite the competition from indigenous isolates of the same species provides further illustration of the potential of exotic species for large-scale microbial application.